Stereoscopic image display device and method

ABSTRACT

A stereoscopic image display and method is provided. The stereoscopic image display device includes: a thin film transistor array substrate, a color filter substrate facing the thin film transistor array substrate, the color filter substrate including a plurality of black matrices, a plurality of black stripes on the color filter substrate, each of the plurality of black stripes corresponding to the black matrices, and a patterned retarder film on the color filter array substrate over the black stripes, wherein at least one of the plurality of black stripes includes a first black pattern and a second black pattern that are spaced apart from each other, such that gaps are disposed therebetween.

CROSS-REFERENCE TO RELATED APPLICATION(S)

This application claims the benefit under 35 U.S.C. §119(a) of KoreanPatent Application No. 10-2011-0078016, filed on Aug. 5, 2011, in theKorean Intellectual Property Office, the entire disclosure of which isincorporated by reference herein for all purposes.

BACKGROUND

1. Field

The following description relates to a stereoscopic image display deviceand method, and more particularly, to a stereoscopic image displaydevice and method which can improve the vertical viewing angle of astereoscopic image and cancel front crosstalk.

2. Discussion of the Related Art

A stereoscopic image display displays a stereoscopic image using astereoscopic technique or an autostereoscopic technique.

The stereoscopic technique, which uses a binocular parallax imagebetween left and right eyes of a user and has a high stereoscopiceffect, includes a glass method and a non-glass method which have beenput to practical use. In the glass method, the binocular parallax imageis displayed on a direct view-based display device or a projector bychanging a polarization direction or in a time division manner, andpolarization glasses or liquid crystal shutter glasses are used toimplement stereoscopic images. In the non-glass method, generally, anoptical plate such as a parallax barrier or the like for separating anoptical axis of the binocular parallax image is provided at the frontsurface or rear surface of a display screen.

FIG. 1 is an example exploded view showing a related art stereoscopicimage display device.

With reference to FIG. 1, the glasses type stereoscopic image displaydevice 1 comprises a thin film transistor array substrate 10, a colorfilter substrate 12 comprising color filters 13 and a black matrix 14,and a liquid crystal layer 15 interposed between the thin filmtransistor array substrate 10 and the color filter substrate 12. Upperand lower polarizations 16 a and 16 b are positioned on the thin filmtransistor array substrate 10 and the color filter substrate 12, apatterned retarder 17 is positioned on the upper polarization 16 a, anda surface-treated protective film 18 is positioned on the patternedretarder 17.

The thus-configured stereoscopic image display device 1 alternatelydisplays a left image and a right image and switches polarizationcharacteristics incident to polarization glasses via the patternedretarder 17. Thereby, the glasses type can implement stereoscopic imagesby spatially dividing left images and right images.

When displaying a stereoscopic image, the stereoscopic image displaydevice determines vertical viewing angle by the width of the blackmatrix, the distance between the color filters and the patternedretarder, etc. The related art stereoscopic image display devicerealizes a vertical viewing angle of 26 degrees by increasing the widthof the black matrix, but the increase in the width of the black matrixleads to a decrease in aperture ratio and brightness.

SUMMARY

Embodiments of the present invention relate to a stereoscopic imagedisplay device and method.

An object of embodiments is to provide a stereoscopic image displaydevice which can improve the vertical viewing angle of a stereoscopicimage and cancel front crosstalk.

Advantages, objects, and features of the disclosure will be set forth inpart in the description which follows and in part will become apparentto those having ordinary skill in the art upon examination of thefollowing or may be learned from practice of the invention. Theobjectives and other advantages of the invention may be realized andattained by the structure particularly pointed out in the writtendescription and claims hereof as well as the appended drawings.

To achieve these objects and other advantages and in accordance with thepurpose according to an aspect of the present invention, a stereoscopicimage display device includes a thin film transistor array substrate, acolor filter substrate facing the thin film transistor array substrate,the color filter substrate including a plurality of black matrices, aplurality of black stripes on the color filter substrate, each of theplurality of black stripes corresponding to the black matrices, and apatterned retarder film on the color filter array substrate over theblack stripes, wherein at least one of the plurality of black stripesincludes a first black pattern and a second black pattern that arespaced apart from each other, such that gaps are disposed therebetween.

According to another aspect, a method of manufacturing a stereoscopicimage display device includes forming a thin film transistor arraysubstrate, forming a color filter substrate facing the thin filmtransistor array substrate, the color filter substrate including aplurality of black matrices, forming a plurality of black stripes on thecolor filter substrate, each of the plurality of black stripescorresponding to the black matrices, and forming a patterned retarderfilm on the color filter array substrate over the black stripes, whereinat least one of the plurality of black stripes includes a first blackpattern and a second black pattern that are spaced apart from eachother, such that gaps are disposed therebetween.

It is to be understood that both the foregoing general description andthe following detailed description are examples and explanatory and areintended to provide further explanation of embodiments of the inventionas claimed.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompany drawings, which are included to provide a furtherunderstanding of the invention and are incorporated on and constitute apart of this specification illustrate embodiments of the invention andtogether with the description serve to explain the principles of theinvention. In the drawings:

FIG. 1 is an example side exploded view showing a related artstereoscopic image display device;

FIG. 2 is an example of a perspective exploded view showing astereoscopic image display device according to an example embodiment;

FIG. 3 is an example of a side view showing a stereoscopic image displaydevice according to a first example embodiment;

FIG. 4 is an example of a top plan view showing the stereoscopic imagedisplay device according to the first example embodiment;

FIG. 5 is an example of an enlarged view of region A of FIG. 3;

FIG. 6 is an example of a pattern diagram for explaining effects of thestereoscopic image display device according to the first exampleembodiment;

FIG. 7 is an example of a side view showing another stereoscopic imagedisplay device according to the first example embodiment;

FIG. 8 is an example of a top plan view showing a stereoscopic imagedisplay device according to a second example embodiment; and

FIG. 9 is an example of a graph of the measurement of front crosstalkversus the vertical viewing angles of stereoscopic image display devicesmanufactured according to a comparative example and example embodiments.

Throughout the drawings and the detailed description, unless otherwisedescribed, the same drawing reference numerals should be understood torefer to the same elements, features, and structures. The relative sizeand depiction of these elements may be exaggerated for clarity,illustration, and convenience.

DETAILED DESCRIPTION

Reference will now be made in detail to embodiments of the presentinvention, examples of which are illustrated in the accompanyingdrawings. In the following description, when a detailed description ofwell-known functions or configurations related to this document isdetermined to unnecessarily cloud a gist of the invention, the detaileddescription thereof will be omitted. The progression of processing stepsand/or operations described is an example; however, the sequence ofsteps and/or operations is not limited to that set forth herein and maybe changed as is known in the art, with the exception of steps and/oroperations necessarily occurring in a certain order. Names of therespective elements used in the following explanations are selected onlyfor convenience of writing the specification and may be thus differentfrom those in actual products.

FIG. 2 is an example of a perspective exploded view showing astereoscopic image display device according to an example embodiment.

With reference to FIG. 2, the stereoscopic image display 100 accordingto an example embodiment may include a display panel DP, a polarizationplate 170, a patterned retarder 180, and polarization glasses 195.

The display panel DP may be, but is not limited to, a liquid crystaldisplay panel. The display panel DP may be a display panel for otherflat display devices, such as a field emission display (FED), a plasmadisplay panel (PDP), a light emitting diode device (LED), etc.

When the display panel DP is implemented as a liquid crystal displaypanel, the stereoscopic image display device 100 may further include abacklight unit (not shown) disposed under the display panel DP and apolarization plate (not shown) disposed between the display panel DP andthe backlight unit. The patterned retarder 180 and the polarizationglasses 195 are stereoscopic image driving elements, which realize abinocular parallax by spatially dividing left images and right images.

The display panel DP may include two glass substrates and a liquidcrystal layer sandwiched therebetween. A thin film transistor array maybe formed on the thin film transistor array substrate. A color filterarray is formed on the color filter substrate. The color filter arraymay include black matrices, color filters, etc. The polarization plate170 may be attached to the color filter substrate, and the polarizationplate 170 may also be attached to the thin film transistor arraysubstrate.

Left-eye images L and right-eye images R may be alternately displayed onthe display panel DP in a line-by-line manner. The polarization plate170 may be an analyzer attached onto the color filter substrate of thedisplay panel DP, which may transmit only a specific linearly polarizedlight out of incident light passed through the liquid crystal layer ofthe display panel DP.

The patterned retarder 180 may include first retarder patterns andsecond retarder patterns which may be alternately disposed in aline-by-line manner. For example, the retarder patterns may be disposedin a line-by-line manner to make an angle of (+)45 degrees and (−)45degrees with an absorption axis of the polarization plate 170.

Each of the retarder patterns may delay the phase of light byλ(wavelength)/4 using a birefringence medium. The optical axis of thefirst retarder patterns and the optical axis of the second retarderpattern may be orthogonal to each other.

Accordingly, the first retarder patterns may be disposed to face linesfor displaying a left-eye image on the display panel DP, and may convertthe light of the left-eye image into first polarized light (circularlypolarized light or linearly polarized light). The second retarderpatterns may be disposed to face lines for displaying a right-eye imageon the display panel DP, and may convert the light of the right-eyeimage into second polarized light (circularly polarized light orlinearly polarized light). In one example, the first retarder patternsmay be implemented by a polarization filter for transmittingleft-circularly polarized light, and the second retarder patterns may beimplemented by a polarization filter for transmitting right-circularlypolarized light.

A polarization film for allowing only the first polarization componentto pass therethrough may be bonded to the left-eye of the polarizationglasses 195, and a polarization film for allowing only the secondpolarization component to pass therethrough may be bonded to theright-eye of the polarization glasses 195. Therefore, a viewer wearingthe polarization glasses 195 may see only a left-eye image with the lefteye and only a right-eye image with the right eye, with an impressionthat an image displayed on the display panel DP is a stereoscopic image.

Hereinafter, a stereoscopic image display device and a method formanufacturing the same according to example embodiments will bedescribed in more detail below. In what follows, the components commonto those in the above-described stereoscopic image display are denotedby like reference numerals, so the descriptions thereof will be madebriefly or omitted for conciseness.

FIG. 3 is an example of a side view showing a stereoscopic image displaydevice according to a first example embodiment. FIG. 4 is an example ofa top plan view showing the stereoscopic image display device accordingto the first example embodiment. FIG. 5 is an example of an enlargedview of region A of FIG. 3. FIG. 6 is an example of a pattern diagramfor explaining effects of the stereoscopic image display deviceaccording to the first example embodiment. FIG. 7 is an example of aside view showing another stereoscopic image display device according tothe first example embodiment.

With reference to FIG. 3, the stereoscopic image display device 100according to the first example embodiment may include a display panel DPincluding a thin film transistor array substrate 110, a color filtersubstrate 120 facing the thin film transistors array substrate 110, anda liquid crystal layer 150 interposed therebetween.

For example, the thin film transistor array substrate 110 may have athin film transistor array. The thin film transistor array may include aplurality of data lines supplied with red, green, and blue datavoltages, a plurality of gate lines (or scan lines) which intersect thedata lines and are sequentially supplied with gate pulses (scan pulses),a plurality of thin film transistors formed at the intersections of thedata lines and the gate lines, a plurality of pixel electrodes forcharging data voltages in liquid crystal cells, and a storage capacitorconnected to the pixel electrodes to maintain the voltages of the liquidcrystal cells.

Common electrodes facing the pixel electrodes to form an electric fieldmay be disposed on the color filter substrate 120 in a vertical electricfield driving type, such as a TN (twisted nematic) mode and a VA(vertical alignment) mode, and may be disposed on the thin filmtransistor array substrate 110 along with the pixel electrodes in ahorizontal electric field type, such as an IPS (in plane switching) modeand an FFS (fringe field switching) mode.

The color filters 135 and a plurality of black matrices 130 disposedtherebetween may be formed on the color filter substrate 120, and anovercoat layer 140 for protecting the color filters 135 and the blackmatrices 130 are formed thereon. The color filters 135 may function toconvert light emitted from the backlight unit and transmitted throughthe liquid crystal layer 150 into red, green, and blue. Also, the colorfilters 135, with the black matrices 130 respectively disposed thereon,may function to separate a left-eye image and a right-eye image. Theovercoat layer 140 may function to reduce a difference in level betweenthe color filters 135 and protect the color filters 135.

In the thin film transistor array substrate 110 and the color filtersubstrate 120, alignment layers for setting a pre-tilt angle of liquidcrystals may be respectively formed on the inner surfaces contacting theliquid crystal layer 150, and a column spacer 145 for keeping a cell gapof the liquid crystal cells may be formed.

A rear indium tin oxide (ITO) 160 may be formed on an outer side of thecolor filter substrate 120, black stripes may be formed on the rear ITO160, the polarization plate 170 may be formed on the black stripes 165,and a patterned retarder film 185 may be formed on the polarizationplate 170.

The rear ITO 160 may externally discharge static electricity generatedon the color filter substrate 120, and may be formed on the entiresurface of the color filter substrate 120. The first black stripes 165corresponding to the black matrices 130 may be formed on the rear ITO160. The above-mentioned polarization plate 170 may be formed on thefirst black stripes 165 to polarize the light transmitted through thedisplay panel DP.

The patterned retarder film 185 may be positioned on the polarizationplate 170. Of the patterned retarder film, as described above, the firstretarder patterns 180 a and the second retarder patterns 180 b may beformed on the protective film 190. The first retarder patterns 180 a maybe disposed to face lines for displaying a left-eye image on the displaypanel DP, and may convert the light of the left-eye image into firstpolarized light (circularly polarized light or linearly polarizedlight). The second retarder patterns 180 b may be disposed to face linesfor displaying a right-eye image on the display panel DP, and mayconvert the light of the right-eye image into second polarized light(circularly polarized light or linearly polarized light). In oneexample, the first retarder patterns 180 a may be implemented by apolarization filter for transmitting left-circularly polarized light,and the second retarder patterns 180 b may be implemented by apolarization filter for transmitting right-circularly polarized light.

The plurality of black stripes 165 formed on the rear ITO 160 may beformed of the same material, such as carbon black, as the black matrices130, and may be formed in regions corresponding to the black matrices130. The plurality of black stripes 165 of embodiments each may includea first black pattern 166 and a second black pattern 167.

For example, as illustrated in FIGS. 4 and 5, at least one of theplurality of black stripes 165 may include a first black pattern 166 anda second black pattern 167 that may be spaced apart from each other. Atleast one of the gaps d1 between the black stripes 165 may be formedlarger than the gaps d2 and d3 between the first black pattern 166 andthe second black pattern 167.

The gaps d2 and d3 between the first black pattern 166 and the secondblack pattern 167 may be formed to overlap with the black matrices 130.The gaps d2 and d3 between the first black pattern 166 and the secondblack pattern 167 may cause light to be transmitted and emitted to theoutside, preventing a decrease in aperture ratio.

As an example, the gaps d2 and d3 between the first black pattern 166and the second black pattern 167 may range from 1 to 15 μm. If the gapsd2 and d3 between the first black pattern 166 and the second blackpattern 167 are greater than or equal to 1 μm, this may provide lesscrosstalk on the front surface. Otherwise, if the gaps d2 and d3 betweenthe first black pattern 166 and the second black pattern 167 are lessthan or equal to 15 μm, this may prevent a decrease in aperture ratio.

As the gaps d2 and d3 between the first black pattern 166 and the secondblack pattern 167 of the plurality of black stripes 165 may be madeequal, the three-dimensional (3D) image quality of each region can bekept uniform. Moreover, the sum of the width d4 of the first blackpattern 166 and the width d4 of the second black pattern 167 may beequal to the width d5 of the black matrices 130.

As shown in FIG. 6, if the width d5 of the black matrices 130 is equalto the sum of the width d4 of the first black pattern 166 and the widthd4 of the second black pattern 167, the first black pattern 166 andsecond black pattern 167 spaced apart from each other can contribute tocancelling front crosstalk and to increasing vertical viewing angle.Moreover, light may transmit through the gaps between the first blackpattern 166 and the second black pattern 167, which may prevent adecrease in aperture ratio.

Consequently, embodiments may reduce front crosstalk, may increasevertical viewing angle, and may prevent a decrease in aperture ratio byforming a plurality of black stripes including a first black pattern anda second black pattern, spaced apart from each other, in the regionscorresponding to the black matrices.

As illustrated in FIG. 7, the stereoscopic image display deviceaccording to the second example embodiment may include an adhesive 168formed between the rear ITO 160 with the black stripes 165 and thepolarization plate 170 to bond the polarization plate 170.

FIG. 8 is an example of a top plan view showing a stereoscopic imagedisplay device according to a second example embodiment. Hereinafter,the same components as the above-described first example embodiment willbe assigned the same reference numerals, and their explanations will besimplified.

With reference to FIG. 8, the stereoscopic image display deviceaccording to the second example embodiment may include a display panelDP including a thin film transistor array substrate 110, a color filtersubstrate 120 facing the thin film transistor array substrate 110, and aliquid crystal layer 150 interposed therebetween.

The color filters 135 and a plurality of black matrices 130 disposedtherebetween may be formed on the color filter substrate 120, and anovercoat layer 140 for protecting the color filters 135 and the blackmatrices 130 may be formed thereon. In the thin film transistor arraysubstrate 110 and the color filter substrate 120, alignment layers forsetting a pre-tilt angle of liquid crystals may be respectively formedon the inner surfaces contacting the liquid crystal layer 150, and acolumn spacer 145 for keeping a cell gap of the liquid crystal cells maybe formed.

In the second example embodiment, unlike the above-described firstexample embodiment, black stripes 165 may be formed on an outer side ofthe color filter substrate 120, and a rear ITO 160 may be formed tocover the black stripes 165. A polarization plate 170 may be formed onthe rear ITO 160, and a patterned retarder film 185 may be positioned onthe polarization plate 170. As described above, the patterned retarderfilm 185 may have first retarder patterns 180 a and second retarderpatterns 180 b formed on a protective film 190. Also, the black stripes165 formed on the top surface of the color filter substrate 120, i.e.,under the rear ITO 160, may have the same configuration as the previousfirst example embodiment, so an explanation thereof will be omitted.

Hereinafter, example embodiments will be disclosed to help understandingof embodiments. However, the example embodiments are merely to explainthe present invention, and not to limit the scope of the presentinvention.

Example Embodiment 1

A plurality of black matrices having a width of 50 μm may be formed onthe bottom surface of a color filter substrate, first and second blackpatterns each having a width of 25 μm may be formed on the top surfaceof the color filter substrate, and the first black pattern and thesecond black pattern may be spaced apart from each other by a gap of 10μm, forming a plurality of black stripes.

Example Embodiment 2

A plurality of black stripes may be formed by spacing the first blackpattern and the second black pattern apart from each other by a gap of15 μm under the same condition as the previous example embodiment 1.

Comparative Example

In the related art given as a comparative example, a plurality of blackstripes are formed, with the first black pattern and the second blackpattern not spaced apart from each other, under the same condition asthe previous example embodiment 1.

Front crosstalk was measured relative to the vertical viewing angles ofstereoscopic image display devices manufactured according to thecomparative example, example embodiment 1, and example embodiment 2 asset forth above, and as shown in FIG. 9. It can be observed that frontcrosstalk decreases as the lowest point of each of the curves of thegraph becomes closer to the horizontal axis, and the vertical viewingangle increases as the center of each curve becomes closer to 0 on thehorizontal axis.

With reference to FIG. 9, example embodiments 1 and 2 showed less frontcrosstalk because the lowest points of the curves were closer to thehorizontal axis than the comparative example. Example embodiment 2showed improved vertical viewing angle compared to example embodiment 1and to the comparative example 1.

As seen from FIG. 9, the stereoscopic image display device according toan example embodiment may reduce front crosstalk and improve verticalviewing angle and aperture ratio by further forming a plurality of blackstripes including a first black pattern and a second black patternspaced apart from each other.

It will be apparent to those skilled in the art that variousmodifications and variations can be made in the organic light emittingdiode display device and method of driving the same of embodiments ofthe present invention without departing from the spirit or scope of theinvention. Thus, it is intended that the present invention cover themodifications and variations of this invention provided they come withinthe scope of the appended claims and their equivalents.

A number of examples have been described above. Nevertheless, it will beunderstood that various modifications may be made. For example, suitableresults may be achieved if the described techniques are performed in adifferent order and/or if components in a described system,architecture, device, or circuit are combined in a different mannerand/or replaced or supplemented by other components or theirequivalents. Accordingly, other implementations are within the scope ofthe following claims.

1-18. (canceled)
 19. A stereoscopic image display device, comprising: athin film transistor array substrate; a color filter substrate facingthe thin film transistor array substrate, the color filter substratecomprising a plurality of black matrices; a plurality of black stripeson the color filter substrate, each of the plurality of black stripescorresponding to the black matrices; and a patterned retarder film onthe color filter array substrate over the black stripes, wherein atleast one of the plurality of black stripes comprises a pair of blackpatterns including a first black pattern and a second black pattern thatare spaced apart from each other, such that a gap is disposedtherebetween, and wherein at least a portion of the first black patternand at least a portion of the second black pattern of the pair of blackpatterns respectively overlap the same one black matrix.
 20. The deviceof claim 19, wherein a width of the gap between the first black patternand the second black pattern of the pair of black patterns ranges from 1to 15 μm.
 21. The device of claim 19, wherein: all the plurality ofblack strips respectively comprises the pair of black patterns includingthe first black pattern and the second black pattern; and a plurality ofgaps respectively positioned between the first black pattern and thesecond black pattern are equal in width.
 22. The device of claim 19,wherein a sum of a width of the first black pattern and a width of thesecond black pattern of the pair of black patterns is equal to a widthof the same one black matrix.
 23. The device of claim 19, wherein adistance between adjacent two black stripes is greater than a width ofthe gap between the first black pattern and the second black pattern ofthe pair of the black patterns.
 24. The device of claim 19, furthercomprising: an adhesive layer between the plurality of black stripes andthe patterned retarder film, wherein the adhesive layer is disposed: inthe gap between the first and second black patterns of the pair of blackpatterns, and between adjacent pair of black patterns.
 25. The device ofclaim 24, further comprising a rear indium tin oxide (ITO) disposed:between the color filter substrate and the plurality of black strips,and between the color filter substrate and the adhesive layer.
 26. Thedevice of claim 25, further comprising a polarization plate between thepatterned retarder film and the adhesive layer.
 27. The device of claim19, further comprising a rear indium tin oxide (ITO) disposed: in thegap between the first and second black patterns of the pair of blackpatterns, and between adjacent pair of black patterns.
 28. The device ofclaim 27, further comprising a polarization plate between the patternedretarder film and the indium tin oxide.
 29. A method of manufacturing astereoscopic image display device, the method comprising: forming a thinfilm transistor array substrate; forming a color filter substrate facingthe thin film transistor array substrate, the color filter substratecomprising a plurality of black matrices; forming a plurality of blackstripes on the color filter substrate, each of the plurality of blackstripes corresponding to the black matrices; and forming a patternedretarder film on the color filter array substrate over the blackstripes, wherein at least one of the plurality of black stripescomprises a pair of black patterns including a first black pattern and asecond black pattern that are spaced apart from each other, such that agap is disposed therebetween, and wherein at least a portion of thefirst black pattern and at least a portion of the second black patternof the pair of black patterns respectively overlap the same one blackmatrix.
 30. The method of claim 29, wherein a width of the gap betweenthe first black pattern and the second black pattern of the pair ofblack patterns ranges from 1 to 15 μm.
 31. The method of claim 29,wherein: all the plurality of black strips respectively comprises thepair of black patterns including the first black pattern and the secondblack pattern; and a plurality of gaps respectively positioned betweenthe first black pattern and the second black pattern are equal in width.32. The method of claim 29, wherein a sum of a width of the first blackpattern and a width of the second black pattern of the pair of blackpatterns is equal to a width of the same one black matrix.
 33. Themethod of claim 29, wherein a distance between adjacent two blackstripes is greater than a width of the gap between the first blackpattern and the second black pattern of the pair of the black patterns.34. The method of claim 29, further comprising: forming an adhesivelayer between the plurality of black stripes and the patterned retarderfilm, wherein the adhesive layer is disposed: in the gap between thefirst and second black patterns of the pair of black patterns, andbetween adjacent pair of black patterns.
 35. The method of claim 34,further comprising forming a rear indium tin oxide (ITO) disposed:between the color filter substrate and the plurality of black strips,and between the color filter substrate and the adhesive layer.
 36. Themethod of claim 35, further comprising forming a polarization platebetween the patterned retarder film and the adhesive layer.
 37. Themethod of claim 29, further comprising forming a rear indium tin oxide(ITO) disposed: in the gap between the first and second black patternsof the pair of black patterns, and between adjacent pair of blackpatterns.
 38. The method of claim 37, further comprising forming apolarization plate between the patterned retarder film and the indiumtin oxide.